In Wellfleet, Massachusetts, on Cape Cod, a dike separates a salt marsh on one side, from a meadow on the other. Soon the dike will be replaced by a bridge with gates that will gradually let water flow back in, reconnecting the areas and enlarging the marsh. Cape Cod National Seashore plant ecologist Stephen Smith says salt marshes provide habitat for birds and fish, filter toxins, and absorb energy from storm surges that threaten homes.

STEPHEN SMITH ( Cape Cod National Seashore ):

There’s kind of been this sea change over the last, I would say, decade of people realizing the value of these systems and wanting to return them back to their original condition.

HIRSHON:

Sea level rise caused by climate change has been eating away at marshes. Smith says restoration projects like this one offer a ray of hope that at least some of these vital habitats can be maintained. I’m Bob Hirshon, for AAAS, the science society.